The standard design for a direct-fired steam generator utilizes a once-through water system in which all feed water pumped into the water-jackets of the combustion chamber and adjacent components is injected into the exhaust stream of hot gases at the bottom the combustion chamber where it is changed into steam by the hot gases. This approach has several drawbacks.
A first drawback occurs during the procedure of starting up the steam generator for operation. A water top-up is needed to ensure that the water jackets are completely filled before igniting the main flame. Since the water enters the water jackets under pressure, any excess is injected into the flame chamber. At this time, no hot gases are present to change the water to steam and this injected water is eventually blown through the steam discharge system and deposited on the crop entering the baler. This causes wet spots in the hay, which may ultimately result in spoilage and, thus, in an entire bale being ruined.
A second drawback occurs during shut-down when water is pumped through the cooling jackets to cool the combustion chamber after the main flame has been extinguished. This cooling water causes the same problems as that caused by the top-up water.
A third drawback occurs when the machine is shut down for the day, and water contained in the water jackets boils because the flow of fresh cooling water ceases when the water pump is shut off. This boiling action results in water running into the exit end of the combustion chamber, where its conical end section guides the water into the cylindrical section of the combustion chamber. This presence of water causes a relatively high humidity to exist in the combustion chamber, then, as the baler sits overnight, moisture will condense on the surfaces of associated parts. It has been observed that when water condenses on the pilot flame igniter or on the flame scanner, ignition difficulties arise and the scanner malfunctions.
Thus, the problem to be solved is to provide the necessary water for cooling the steam generator and for producing steam without causing the above-noted problems.